Maximum Arctic sea ice cover. Composite satellite image centred on the Black Sea showing the extent of seasonal maximum ice cover (white). Data for Arctic sea ice extent (top) was collected on March 9 2006 and data for landcover is the average from March 2004. The majority of Western Europe is ice free because of the warming effect of the Gulf Stream, a warm current in the western Atlantic ocean. The maximum extent of Arctic sea ice cover has decreased significantly in recent years, a phenomenon attributed to climate change. Data obtained by the Terra and Aqua satellites.